In this question, we need to identify the type of triangle based on its angles. The triangle has angles of $39^\circ$, $50^\circ$, and $91^\circ$.

Explanation:

1. Right Triangle: A triangle with exactly one $90^\circ$ angle.
2. Obtuse Triangle: A triangle with one angle greater than $90^\circ$.
3. Acute Triangle: A triangle where all angles are less than $90^\circ$.
4. Equiangular Triangle: A triangle where all three angles are equal, each being $60^\circ$.

Since this triangle has one angle that is $91^\circ$, which is greater than $90^\circ$, it qualifies as an obtuse triangle.

The correct answer should be:

• Obtuse

Would you like further details or have any questions?

Here are five related questions to expand understanding:

1. What is the definition of an isosceles triangle?
2. How do you determine if a triangle is a right triangle based on its angles?
3. Can a triangle have more than one obtuse angle? Why or why not?
4. What makes a triangle equilateral?
5. How can we classify triangles based on side lengths?

Tip: Remember that a triangle can only have one angle above $90^\circ$, which makes it obtuse.